Electromagnetic valve for gaseous fluids

ABSTRACT

An electromagnetic valve for a gaseous fluid includes a combination of an electromagnetic circuit which when activated generates an electromagnetic force for mechanical opening or closing of the valve and a movable disk formed member at least part of which is included in the electromagnetic circuit. The disk formed member is guided in a linear movement perpendicular to the surface of the disk formed member. The valve further includes a valve seat cooperating with the disk formed member providing the mechanical closing and sealing of the valve. A resilient member acts on the disk formed member and a metering device in the form of a restriction arranged immediately downstream of the valve seat creates sonic conditions for the gas flow which makes the gas flow with the valve open independent of fluctuations in the downstream pressure.

TECHNICAL FIELD

The present invention relates to an electromagnetic valve for gaseousfluids. This type of valve has a special application as injector valvefor gaseous fuels for internal combustion engines. The inventiontherefore also relates to an internal combustion engine provided withone or several such valves.

BACKGROUND ART

The problems caused by atmospheric pollution by means of exhaust gasesfrom internal combustion engines such as car motors incite scientistsand car manufacturers to look for new fuels and alternate fuels like forinstance compressed natural gas or liquefied petroleum gas (LPG) whichpotentially offer an important reduction of the emission of pollutinggases and greenhouse gases.

The present solutions for injection and metering of these new fuels foran internal combustion engine offer however not yet performances equalto the solutions used for normal petrol.

The principle for the known fuel systems for metering and mixing agaseous fuel with inlet air to an internal combustion engine are basedon the Venturi effect or on continuous injection of fuel. These systemshave, however, typically an important number of mechanical componentsand do not offer the response times adequate to satisfy the sometimesimportant variations in the demand for fuel by the engine.

Thus, when these known injection systems for gaseous fuel are workingtogether with for instance an associated exhaust gas purification systemof the three-way catalytic converter type with lambda-probe control,their characteristics do not allow for the maintenance of the air tofuel ratio at the desired value during fast transitions in the engineload and speed in order to give an optimal purification of the exhaustgases.

DISCLOSURE OF THE INVENTION

One object of the present invention is to provide an electromagneticvalve for general gaseous fluids which can be used in many industrialapplications in which there is a need for a simple wear resistant valvewith an extremely short response time.

Another object of the invention is to provide an electromagneticinjector valve for gaseous fuels to e.g. an internal combustion engine.Such an injector valve could be mounted on the inlet or inlet manifoldof an internal combustion engine for injecting the fuel. Due to theshort response time of the valve it could be operated in pulsating mode.

The total response time for a traditional injection system for gaseousfuel is due to the operation of the actuator or actuators which are usedfor metering the fuel, the time for the transport of the gas mixturethrough the inlet tube or manifold to the respective cylinder and thecharacteristics for the transport of the fuel through the feeding tubesto the manifold.

The above and further objects are achieved by means of the presentinvention which is characterised in that the valve comprises:

an electromagnetic circuit which when activated generates anelectromagnetic force for mechanical opening or closing of the valve,

a movable disk formed member at least part of which is included in saidelectromagnetic circuit and which disk formed member is guided in alinear movement perpendicular to the surface of said disk formed member,

a valve seat co-operating with the disk formed member providing themechanical closing and sealing of the valve,

a resilient means which acts on the disk formed member,

a hole arranged downstream said valve seat the diameter of which holepreferably defines a sonic section for the gas flow which makes itpossible to precisely adjust the quantity of gas let through as afunction of the time during which the valve is in its open positionirrespective of the downstream pressure.

Important advantages with a valve according to the invention is that itonly has one (two if you count the spring) moving part(s), low inertia,extremely short response time and that it is very wear resistant.

When this type of valve is used as an injector valve for gaseous fuelfor an internal combustion engine it makes possible the use of apulsating mode for the injection of gas into the air flow introducedthrough the inlet or inlet manifold into the internal combustion engineallowing an optimal mixing of the two flows.

Due to the very simple but original design the reliability and life timeare excellent.

BRIEF DESCRIPTION OF THE DRAWINGS

Other objects, uses and advantages of this invention will be apparentfrom the reading of this description which proceeds with reference tothe accompanying drawings forming part thereof and wherein:

FIG. 1 shows a section through the electromagnetic valve for a gaseousfluid according to the invention.

FIG. 2 shows one embodiment of the lower surface of the disk formedmember 17.

FIG. 3 shows a section through the disk formed member 17 according toFIG. 2.

FIGS. 4 and 5 show two other embodiments of the disk formed member.

FIG. 6 shows an internal combustion engine With an injector valveaccording to the invention.

DETAILED DESCRIPTION OF THE INVENTION

The invention will now be further described by means of a particularembodiment.

FIG. 1 shows a section through an electromagnetic valve for gaseousfluids according to the invention. This particular embodiment of thevalve could be used as an electromagnetic injector valve for gaseousfuels for an internal combustion engine. Due to its characteristics itcould in that particular application be controlled in order to giveindirect, pulsating injection of gaseous fuels under pressure into theengine. Indirect injection refers to the injection mode according towhich the gaseous fuel is added to the flow of air fed to the cylinderor cylinders. The valve could be mounted very close to the inlet of themotor in order to give a very short over all response time for the fuelsystem. On a multiple cylinder engine a common valve could be used forall cylinders with a distribution of the air-gas mixture through themanifold to each respective inlet. In another configuration one separatevalve for each cylinder could be mounted on the manifold close to therespective inlet. This gives the advantage of individual metering thefuel to each respective cylinder.

The electromagnetic valve with the general designation 10 comprises amagnetic circuit having a fixed armature 12 and a disk formed member 17forming a movable part of said magnetic circuit It should be noted thatonly part of the disk formed member has to be able to conduct themagnetic field. A solenoid coil 13 is arranged in an annular groove inthe fixed armature 12. Electrical connections 33 on the solenoid coilare arranged to receive electrical energy which allows the activation ofthe electromagnetical valve by generating a magnetic force which willdisplace the disk formed member 17.

An annular valve seat 24 is arranged to co-operate with the disk formedmember and a resilient member in e.g. the form of a spring 15 is in thisembodiment biasing the disk formed member into contact with the valveseat 24 when the valve is not activated. The valve is thus normallyclosed A general purpose valve of this type could of course be designedto be normally open.

In the illustrated embodiment the disk formed member 17 is circular andis provided with a concentric cylindrical guiding member or shaft 34fixed to and arranged perpendicularly to the upper surface of the diskformed member for guiding the movement of said disk formed member in adirection perpendicular to the surface of the disk.

The guiding member 34 of the disk formed member 17 is in this embodimentarranged in an appropriate slide bearing 14 at the center of the fixedarmature 12. The bearing could be of the self lubricating type.

The resilient member 15 is in this case arranged between the guidingmember and the fixed armature. In the embodiment illustrated in FIG. 1the guiding member 34 forms a tube the cylindrical interior 35 of whichis arranged to receive the lower part of said resilient member in theform of a spring 15. The upper part of the spring 15 is arranged in acylindrical cavity 37 in the center of the armature 12. The cylindricalexternal surface of the guiding member is sliding in the bearing 14 andis guiding the disk formed member 17 in its movement.

In other embodiments of the valve according to the invention the guidingof the disk formed member could be achieved at the periphery of saiddisk. In that case no central guiding member 34, and co-operating slidebearing 14 will be necessary. The resilient means 15 could of coursealso be arranged at the periphery of the disk formed member and does nothave to have the form of a spring. It could for instance be realized inthe form of a ring of elastic material.

In order to keep the response time of the valve small it is importantthat there is always the same pressure on both sides of the disk thusalso at start up when pressurised gas suddenly is entering the inlet 26of the valve. This can be achieved by means of e.g. a by-pass channel inthe body of the valve letting both sides of the disk communicatepneumatically. Appropriate holes in the disk could give the same result.The gas could also be allowed to circulate around the edge of the diskbetween the disk and the inner surface of the valve housing. In order toquickly equilibrate the pressure on the two sides of the disk formedmember a thin disk provided with at least one radial slot starting fromthe periphery of the disk could be arranged on top of the disk formedmember 17.

In a particular embodiment of the valve according to the invention asillustrated in FIGS. 1-3 for use as an injector valve the disk formedmember is only moving 0.3 mm which means that the gas turbulence aroundthe edge is of negligible importance.

The disk 17 could also have a considerably smaller diameter than isshown in FIG. 1 and be provided with impeller blades at the periphery.

In the illustrated embodiment the activation of the electromagneticcircuit will move the disk formed member upwards in FIG. 1 and thus openthe valve.

An inlet opening 26 for gaseous fluid of fuel is arranged on the side ofthe body 18 of the injector valve The inlet opening could of course bearranged differently.

The annular valve seat 24 is sealing against the lower surface of thedisk formed member 17 at rest. Preferably a ring 21 of e.g. a somewhatelastic material like a polymer forms the seat. This allows on one handthe absorption of the energy of the shock when the disk is landing onthe seat due to the deactivation of the solenoid 13, and on the otherhand it allows for excellent sealing of the valve so that the gaseousfluid can not circulate from the inlet 26 through the valve to theoutlet conduit 36 when the valve is closed.

When the solenoid 13 is electrically activated, the disk formed member17 at least part of which is included in the electromagnetic circuitmoves from the lower position towards an upper position in FIG. 1 andallows the flow of gaseous fluid from the inlet conduit 26 via a coaxialannular cavity 27 arranged under the disk to further pass between thedisk and the annular seat in the direction of the downstream passage 23and the outlet conduit 36. The sectional area of the passage 23 of thevalve is in this embodiment precisely defined in order to get a sonicflow of the gaseous fluid through the valve. This means that theflowrate will be independent of the pressure on the downstream side ofthe valve which is very important in an application as injector valve asthis pressure changes considerably during the engine working cycle. Atthe same time the opening between the seat 24 and the disk in the fullyopen position of the valve is defined so that it is much bigger than thearea of the hole 23 which will allow for the sonic flow in the hole 23.Thus the flow of gaseous fluid only depends on the pressure of thegaseous fluid on the inlet to the valve 10.

In a preferred embodiment the disk formed member 17 is provided withgrooves 25 arranged radially on its lower surface as shown in FIG. 2.These grooves have an inclined section which is causing a rotation ofthe disk 17 when the gaseous fluid circulate from the inlet conduit 26through the valve towards the outlet conduit 36. The stepwise rotationof the disk 17 allows for a uniform wear of the seat 24, the disk 17 inthe area where it touches the seat 24 in the closed position, theguiding member 34 on the disk 17 and the slide bearing 14.

The rotation of the disk could also be achieved by means of e.g. throughholes having side walls inclined in relation to the lower and uppersurfaces of the disk 17 or slots 28 arranged radially in the disk 17also having an inclined section.

Outside the central area of the disk which is cooperating with the valveseat disk material could be removed in order to lower the mass of thedisk 17.

When the valve is used as an injector valve for an internal combustionengine 38 the electrical conductors 33 of the solenoid 13 could beconnected to a control unit 39 which delivers the control signal foractivating the valve. Preferably a number of probes 40, 41, . . .arranged on the engine are measuring relevant control parameters whichare fed to the control unit in which a calculation according to someappropriate control algorithm is carried out and a resulting controlsignal is generated. This arrangement allows for the injection of agaseous fuel with a variable duration and variable frequency, thus witha variable volume, and with a variable phase. The injector valve couldconsequently deliver fuel at any particular moment of the cycle of theengine, even when the respective inlet valve(s) of the engine is (are)closed. The appropriate air-gas mixture is in such a case momentarilystored in the manifold waiting for the next opening of the respectivevalve.

What is claimed is:
 1. An electromagnetic valve for a gaseous fluidcomprising a combination of: an electromagnetic circuit which whenactivated generates an electromagnetic force for mechanical opening orclosing of the valve; a movable disk formed member at least part ofwhich is included in said electromagnetic circuit and said disk formedmember is guided in a linear movement perpendicular to a surface of saiddisk formed member; a valve seat cooperating with the disk formed memberproviding the mechanical closing and sealing of the valve; a resilientmember which acts on the disk formed member; and a metering member inthe form of a restriction arranged immediately downstream of the valveseat creating sonic conditions for the gas flow which makes the gas flowwith the valve open independent of fluctuations in the downstreampressure; said movable disk formed member has a circular form and isprovided with a concentric cylindrical guiding member or shaft fixed toand arranged perpendicularly to an upper surface of the disk formedmember arranged in an appropriate slide bearing at a center of a fixedarmature of the electromagnetic circuit for guiding the movement of saiddisk formed member in a direction perpendicular to the surface of thedisk.
 2. Electromagnetic valve according to claim 1, characterised inthat said slide bearing (14) does not need lubrication.
 3. Theelectromagnetic valve according to claim 1, wherein said valve seat hasan annular form and seals against a lower surface of the disk formedmember at rest.
 4. The electromagnetic valve according to claim 1,wherein said valve seat is provided with a ring of an elastic materialwhich allows the absorption of energy of a shock when the disk lands onthe seat due to deactivation of a solenoid of the electromagneticcircuit thereby limiting rebounds, and allows for sealing of the valvewhen closed.
 5. The electromagnetic valve according to claim 1, whereinsaid resilient member has the form of a spring arranged at the center ofthe disk formed member.
 6. The electromagnetic valve according to claim1, wherein said disk formed member is provided with grooves arrangedradially on a lower surface, said grooves have an inclined section whichcauses a rotation of the disk when the gaseous fluid circulates from aninlet conduit of the valve, through the valve towards an outlet conduitof the valve.
 7. The electromagnetic valve according to claim 1, whereinsaid disk formed member is provided with slots arranged radially in thedisk having an inclined section which causes a rotation of the disk whenthe gaseous fluid circulates from an inlet conduit of the valve throughthe valve towards an outlet conduit of the valve.
 8. The electromagneticvalve according to claim 1, wherein said disk formed member is providedwith at least one through hole having side walls inclined in relation toa lower surface and the upper surface of the disk which will cause arotation of the disk when the gaseous fluid circulates from an inletconduit of the valve through the valve towards an outlet conduit of thevalve.
 9. An internal combustion engine comprising: at least oneinjector valve for gaseous fuel, said injector valve comprising acombination of: an electromagnetic circuit having an activating coil,said electromagnetic circuit when activated generates an electromagneticforce for mechanical opening or closing of the valve; a movable diskformed member at least part of which is included in said electromagneticcircuit and said disk formed member is guided in a linear movementperpendicular to a surface of said disk formed member; a valve seatcooperating with the disk formed member providing the mechanical closingand sealing of the valve; a resilient member which acts on the diskformed member; and a metering member in the form of a restrictionarranged immediately downstream of the valve seat creating sonicconditions for the gas flow which makes the gas flow with the valve openindependent of fluctuations in the downstream pressure; a control unitconnected to said activating coil; and at least one probe arranged onthe engine to measure relevant control parameters and feed correspondingelectrical signals to said control unit arranged to calculate accordingto some appropriate control algorithm a resulting control signal whichis fed to electrical connections on the activating coil which allows theactivation of the electromagnetic valve, making it possible to inject apredetermined amount of gaseous fuel at any particular moment of thecycle of the engine into the air fed